(19)
(11) EP 1 191 416 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
29.10.2003 Bulletin 2003/44

(43) Date of publication A2:
27.03.2002 Bulletin 2002/13

(21) Application number: 01000476.0

(22) Date of filing: 20.09.2001
(51) International Patent Classification (IPC)7: G05F 1/575
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 20.09.2000 US 665816

(71) Applicant: Texas Instruments Inc.
Dallas, Texas 75251 (US)

(72) Inventor:
  • Xi, Xiaoyu (Frank)
    Texas 75025, Plano (US)

(74) Representative: Holt, Michael 
Texas Instruments Ltd., EPD MS/13, 800 Pavilion Drive
Northampton Business Park, Northampton NN4 7YL
Northampton Business Park, Northampton NN4 7YL (GB)

   


(54) Voltage regulator


(57) A high power supply ripple rejection (PSRR) internally compensated low dropout voltage regulator 200 using an output PMOS pass device 206. The voltage regulator 200 uses a non-inversion variable gain amplifier stage 202 to adjust its gain in response to a load current passing through the output PMOS device 206 such that as the load current decreases, the gain increases, wherein a second pole associated with the voltage regulator 200 is pushed above a unity gain frequency associated with the voltage regulator 200. The non-inversion variable gain amplifier 202 is further operational to adjust its gain in response to a load current passing through the power PMOS device 206 such that as the load current increases, the gain decreases, wherein the voltage regulator unity gain bandwidth associated with the loop formed by the compensation capacitor 208 is kept substantially constant.






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